Late Successional Forest Management Project

It is hard to say with certainty what Appalachia’s forests looked like before European settlement. What is known is that Native Americans used fire extensively to manage Appalachia's forests. Fires encourage fruit and berry production, expose nuts for collection, control pests, concentrate game, clear land for agriculture, and fireproofs villages. As a result, the understory was fairly open, facilitating hunting and travel.  These fires helped fire adapted species, particularly oaks, pines and chestnuts to thrive.  

In the 1600s, English explorer Captain John Smith described Maryland's forests as open and almost park-like, with  a few clearings.  Other than occasional fires set by Indigenous Peoples for hunting or to make clearings for growing crops, Maryland’s forests were virtually untouched, especially in the Western part of the state. 

Written in 1728 in Southern Appalachia, William Byrd's T he History of the Dividing Line Betwixt Virginia and North Carolina  frequently describes a complex forest structure. He describes significant disturbances such as swaths of trees that were blown down, which created large canopy gaps and tree mortality due to insects and fires which created many snags. He frequently comes across coarse woody debris on the ground and patches of thick undergrowth, mainly saplings. Although he does not measure them, he describes tall and old poplars, hickories and oaks.

George Washington  recorded the size of several large trees in his journal  while he was exploring in what is now West Virginia. "Just as we came to the hills, we met with a Sycamore.....of a most extraordinary size, it measuring three feet from the ground, forty-five feet round, lacking two inches; and not fifty yards from it was another, thirty-one feet round." In other words, he found one tree more than 14 feet in diameter, and another almost 10 feet in diameter.

The arrival of European colonists had an enormous impact on the forest. To many of them, the forest was seen as an obstacle. The forest interfered with the colonists’ agricultural practices, and harbored predators. So, colonists cleared swaths of forest, usually to  grow cash crops  or to clear land for  grazing.  As colonists moved west, logging accelerated, since more wood was needed for structures and fuel.

 By the late 1800s,  logging in Appalachia was in full swing. This logging was mainly enabled by railroads. Railroads, such as the B&O, connected the Appalachians to industrial centers. But smaller, narrow gauge railroads really opened up the forests, while  steam powered lumber mills  allowed for the rapid processing of cut trees. These factors led to the rapid deforestation of Appalachia.

Of course, such widespread clearing was not sustainable. For instance,  nearly all of West Virginia was deforested.  In the early 1900s, the conservation movement  began to grow , eventually leading to the establishment of state forestry agencies, National Parks, and National Forests. Unfortunately, much of the damage to Appalachia’s forests had already been done. As bad as the logging practices of the time were,  intense forest fires (frequently ignited by locomotives)  killed seedlings and destroyed seeds. The  effects of soil disturbance  were even worse. As a result, the forests here today look very different, even if many of the same tree species are present. 

In Appalachia, the Civilian Conservation Corps (CCC), established by Franklin D. Roosevelt in 1933 during the Great Depression, played an important role in helping the forest recover. Across the country, the CCC  planted more than 3 billion trees.  In the Monongahela National Forest in West Virginia alone, the CCC  planted more than 10 million trees.  Conservation efforts, coupled with more sustainable timber harvesting practices, have allowed forests in the Appalachians to regenerate to where they are today.

There isn’t actually a commonly accepted definition of old growth. To some people, old growth means forests that are older than 150 years. To others, old growth forests are forests undisturbed by human impact. Regardless of how it is defined, there are characteristics commonly found in older, late successional forests.

Every state defines old growth differently. Maryland defines old growth forests as areas greater than 5 acres where the oldest trees are at least half as old as the maximum lifespan for trees of that species. These areas also need to exhibit most of the following: shade tolerant species of all sizes and age classes, randomly distributed canopy gaps, multilayered canopy, and an accumulation of dead wood.

Old growth forests are important because they provide habitats for native plants, animals and fungi. They also tend to be more diverse, and because of that diversity, they are more resilient to climate change and invasive species.

Of course, early and mid successional forests are very important too, and a healthy landscape will have a mix of early successional, mid successional and old growth forests. However, old growth forests are underrepresented across Appalachia.

Despite the above diagram, It is important to note that forest succession does not always follow a linear path. For instance, at our Savage River State Forest demonstration site, a large moth infestation caused many large trees to die. As a result, some areas lost trees that the state of Maryland would consider old growth. However, surviving and new trees will continue to grow and eventually the area will again have trees considered old growth. Regression to earlier successional stages is not necessarily a bad thing, but just a step on the way to developing a complex canopy structure.

In the above depiction, we see that as the forest ages, its structure becomes more complex. The old growth forest has old and young trees, as well as standing dead trees and woody debris on the ground. Some of these characteristics are already present at our demonstration site in Savage River State Forest.

There is not some magic age where a forest develops these old growth characteristics. They develop over time. Since many of the forests here have been logged so recently, they have not developed these characteristics.

Diversity is key to ensuring climate resilience at landscape scale. As diverse as old growth forests are, it is still vital that early and mid-successional forests are present across the landscape. Again, in this project we are focusing on developing old growth characteristics because they are underrepresented in the landscape. For this project, we worked with the  Northern Institute of Applied Climate Science  to identify challenges and opportunities, and create plans.

Not only are old growth forests more resilient to climate change, they provide an important migratory corridor. As the climate changes, plants and animals will need to migrate to areas where the weather is suitable. From the map below, we can see that the Appalachians play an important role in allowing animal species to migrate. Species will generally migrate north and towards higher elevation areas.

It's important to protect these corridors holistically to maintain connections. In the same way that a damaged bridge on the highway could stop you from getting to your destination, these connections are vital to ensure that these species can migrate to new areas. We are also working to create a network of these corridors.  You can learn more about our resilient connected network here. 

Because old growth forests are so underrepresented in the Appalachians, and most remaining old growth is already protected, it's important to allow for the future development of old growth forests. Old growth traits tend to develop once some trees in a stand reach 100 years of age. Forests around this age are beyond the age of maximum commercial value, and often slip through conservation efforts.

We will have several demonstration sites established with different landowners and management priorities. For now, we have a 59-acre demonstration site located in Western Maryland at Savage River State Forest. We chose this site because it has lots of oaks (which are a late successional species), lots of snags because of a  moth  infestation, and there are very few invasive plant species present. These factors made it an ideal candidate for structural complexity enhancement. The slideshow below shows some of what we found at our demonstration site. In the maps, you will notice that we did not collect data in the northeastern section of our site. That's because this area of our site was logged, and there aren't any large trees or late successional traits in that section.

We collected location information in the fall of 2020 using a combination of ArcGIS Survey123 (for points and images), and Avenza (for recording tracks and navigating). We also collected tree species information, diameter at breast height, and took pictures of every feature we found.

There are several traits to look for or create when enhancing a forest's structure. It's important to note that managing for late successional forest characteristics does not prevent activities such as timbering. There is a sliding scale of approaches that allow for restoration intensity consistent with other management goals. Our Savage River State Forest Demonstration site is simply an area that is being managed specifically for late successional characteristics. We are currently looking to apply these techniques with private landowners with different management objectives.

Legacy trees are the main canopy and are future sources of old growth structure. These trees aren't harvested and are left to grow larger and die. Once these trees die, they will likely remain as standing snags, before falling over and turning into woody debris. These legacy trees can be either scattered throughout a large area or retained in groups.

For our purposes at our demonstration site, legacy trees are generally trees greater than 15 inches in diameter. The smaller legacy trees are usually conifers, specifically hemlocks. We collected the location, species, diameter, and pictures for 482 legacy trees. Of these, 201 are red oaks, 198 are chestnut oaks, 53 are white oaks, 22 are hemlocks, and the remainder are a mix of other deciduous trees. The average DBH is 18.3 inches and the largest is 34.4 inches.

Legacy trees do not necessarily have to be large. For example, our smallest legacy tree is a hemlock that's 7.1 inches in diameter. Since there's a lack of conifers at our site, we would like the hemlocks to remain for a while.

Other than selecting legacy trees and not harvesting them, there is little that can be done to guarantee they will be large. Something that we are doing is girdling other trees around some legacy trees that are in the understory. This reduces competition, allows more sunlight to reach the legacy tree and creates snags.

You can click on each point to see its species, diameter at breast height, and other observations. The map legend can be opened by clicking on the button in in the bottom left. You can also drag and zoom like in Google Maps. There may be typos, but this is the data as we collected it. If the area you click has overlapping features, clicking the right arrow in the bottom right of the pop up will show you the next feature.

Snags are standing dead trees. In general, the snags we recorded the location of are larger than 20 inches in diameter. We collected the locations and diameter for 482 snags, the largest of which was 34.4 inches in diameter.

Snags are an important part of enhancing a canopy's complexity. They provide an important habitat for birds and insects, and will provide coarse woody debris and pit and mound topography when they fall. At our Savage River demonstration site, there was a large gypsy moth infestation in 2008, causing a significant amount of mortality. Because of that, we did not need to create many snags. In an area with fewer snags, we would select more trees to girdle. We did end up girdling 14 trees at our Savage River site, mainly to reduce competition around and release legacy trees.

The easiest way to create snags is by girdling. Girdling removes a strip (or strips) of bark, killing the tree.

You can click on each point to see its diameter at breast height and notes (if any). The map legend can be opened by clicking on the button in in the bottom left. You can also drag and zoom like in Google Maps. There may be typos, but this is the data as we collected it. If the area you click has overlapping features, clicking the right arrow in the bottom right of the pop up will show you the next feature.

Coarse woody debris is fallen trees or large branches on the forest floor, and is a hallmark of late successional canopy structure. Coarse woody debris provides an important role in nutrient cycling, provides micro-habitats, and can help stabilize soil on steep hills. Additionally, research suggests that coarse woody debris can reduce the effects of deer browse on young trees.

Most of the coarse woody debris at our demonstration site is small, consisting mainly of the tops and branches of larger standing snags. However, since there is so much of it, we did not feel the need to create more.

Pit and mound topography occurs when a tree or snag falls and is uprooted. Pit and mound topography is a characteristic of old growth forests, and creates diverse micro-habitats.

Canopy gaps are open spaces in a forest's canopy that allow sunlight to reach the forest floor. We marked the location of one large canopy gap at our Demonstration Site. Because of large amounts of coarse woody debris, it was difficult to create an accurate outline by walking around it. There are many smaller canopy gaps that we did not mark.

Canopy gaps increase representation of mid-shade tolerant species and create a multi-aged forest. Canopy gaps created by windthrow events (trees being blown over) or senescence (trees dying of old age) are preferable to canopy gaps created by pests (such as a an insect infestation). That is because pest associated canopy gaps generally result from the death of one tree species.

A major climate change impact on this area will be more frequent and severe wind and ice storms. According to the Northern Institute of Applied Climate Science, canopy gaps with an orientation and shape informed by prevailing winds can reduce the severity of wind storms on a forest. Therefore, these canopy gaps will help our demonstration site be more resilient to climate change.

Canopy gaps can be created by girdling single trees, small groups of trees or felling trees in a specific direction. When creating these gaps, we need to make them in shapes that will reduce the risk of windthrow on trees that are not killed.

Tree plantings are an easy way to increase the diversity of tree species, sizes and ages. We planted trees in patch reserves, outside of patch reserves and in canopy gaps. When selecting tree species to plant, it is important to not just plant trees that will grow there now. Because of habitat changes due to climate change, different trees will be adapted to these forests in the future. A good tool for determining how climate change will affect a forest's tree composition is the  Climate Change Atlas  from the Northern Institute of Applied Climate Science.

The simplest way to think of a patch reserve is as a group of legacy trees dedicated to developing old growth or late successional structure. Our patch reserves are centered around not just legacy trees, but also around other old growth features. Some examples are pit and mound topography, large amounts of coarse woody debris and snags containing cavities.

In this map, you can navigate like Google Maps, but you can also slide the bar in the middle to see the relationship between legacy trees, snags, and patch reserves. You can open the legend by clicking the button in the bottom left corner. If the area you click has overlapping features, clicking the right arrow in the bottom right of the pop up will show you the next feature.

 1 hour presentation on our project 

 A Forest Manager's Guide to Restoring Late Successional Forest Structure 

 Overview of Old Growth Restoration Methods 

 1 Hour Webinar on Restoring Old Growth Characteristics 

 23 Minute Video on Late Successional Forest Management 

 U.S. Forest Service Climate Change Atlas 

 U.S. Forest Service Climate Change Tools